| At present,the water pressure of the Bin 649 block rises,the daily water injection is small,the water injection effect is not satisfactory,and the overall lack of attention is serious.Therefore,it is necessary to carry out an in-depth study on the type of damage and damage mechanism of the reservoir during the water injection process,and formulate corresponding reservoir protection measures for the current water injection situation of the Bin 649 block.Scanning electron microscopy,X-ray diffraction,cast thin section and nuclear magnetic resonance techniques were used to determine the clay mineral content,type and micro-permeability structure of the reservoir.Potential damage factors of the reservoir were analyzed;reservoirs were studied through reservoir sensitivity experiments.Layer sensitive type and damage mechanism;According to the water quality analysis of on-site injection water,the damage of the core water permeability exceeded the influent water quality factors;combined with the analysis of the historical production dynamic data of oil and water wells,the degree of damage to the reservoir caused by irrational water injection was discussed.The results of reservoir sensitivity tests showed that the reservoir sensitivity index was 0.35,and it was moderately weak and sensitive;the water sensitivity index was 0.72,it was medium and strong water sensitive;the soil acid sensitivity index was 0.34,belonging to weak soil acid sensitivity;salt sensitivity The degree of 0.05,no salt sensitivity.The results of on-site injection water quality analysis showed that the suspended solids content at the wellhead was 6.6 mg/l,the median particle diameter was 0.475 μm,and the wellhead oil content was 2.7 mg/l.According to the industrial standards for water quality analysis,none met the standard.The damage test of core water permeability exceeding the standard of injected water showed that the content of suspended solids,particle size,oil content,bacteria content and type all have important influence on the damage of core.The particle size of suspended particles is controlled at 0.3μm,the content is within 1mg/l,the damage is less than 20%,the oil content is within 3mg/l,and the damage is less than 10%;the content of saprophytic bacteria and iron bacteria is controlled within 50mg/l The core damage is less than 10%.There are three main types of reservoir damage assessment mechanisms: one is reservoir sensitive damage;the other is damage caused by unqualified injection water quality;and the third is unreasonable water injection damage to reservoirs. |
